mirror of
https://github.com/eried/portapack-mayhem.git
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72 lines
1.7 KiB
C++
72 lines
1.7 KiB
C++
/*
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* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __SYMBOL_CODING_H__
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#define __SYMBOL_CODING_H__
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#include <cstdint>
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#include <cstddef>
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namespace symbol_coding {
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class NRZIDecoder {
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public:
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uint_fast8_t operator()(const uint_fast8_t symbol) {
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const auto out = (~(symbol ^ last)) & 1;
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last = symbol;
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return out;
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}
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private:
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uint_fast8_t last { 0 };
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};
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class Unstuff {
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public:
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uint_fast8_t is_stuffing_bit(const uint_fast8_t symbol) {
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history = (history << 1) | (symbol & 1);
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return (history & mask) == match;
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}
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void configure(
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const uint32_t pattern,
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const size_t length
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) {
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// Ensure that length=0 (unstuffing disabled) never matches.
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match = length ? pattern : 1;
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mask = (1U << length) - 1;
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reset();
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}
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void reset() {
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history = 0;
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}
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private:
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uint32_t history { 0 };
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uint32_t match { 0b111110 };
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uint32_t mask { 0b111111 };
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};
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} /* namespace symbol_coding */
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#endif/*__SYMBOL_CODING_H__*/
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